In vehicle design, fuel economy is becoming increasingly important. To that end, fuel conservation and engine system design play a significant role. In addition, with the popularity of sport utility vehicles and performance luxury cars, and with increasing competition in the automotive market, superior engine refinement coupled with strong engine performance are necessary deliverables for an engine to satisfy many of today's automotive consumer requirements.
To satisfy the performance aspect, larger displacement engines, such as a V-6 or V-8 engine, are typically developed for these vehicles. As is known, these larger displacement engines generally do not realize the same fuel economy as a smaller displacement engine. To that end, variable displacement engines can provide for fuel economy benefits by operating on the principle of cylinder deactivation. During operating conditions that require high output torque, such as acceleration, every cylinder of a variable displacement engine is arranged to be activated. In contrast, for low load conditions, such as steady cruising, cylinders may be deactivated to improve fuel economy for the variable displacement engine vehicle.
While such variable displacement engines provide advantages of improved fuel economy, conventional cylinder deactivation systems of these arrangements rely on add-on engine componentry, such as externally coupled hydraulic fluid passages, that increase engine cost and complexity as well as create additional sources for potential hydraulic fluid leakage from the engine.